/**
 * The MIT License
 * Copyright (c) 2014-2016 Ilkka Sepp�l�
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.iluwatar.commander;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Hashtable;
import java.util.Random;
import com.iluwatar.commander.exceptions.DatabaseUnavailableException;

/**
 * Service class is an abstract class extended by all services in this example. They
 * all have a public receiveRequest method to receive requests, which could also contain
 * details of the user other than the implementation details (though we are not doing
 * that here) and updateDb method which adds to their respective databases. There is a
 * method to generate transaction/request id for the transactions/requests, which are
 * then sent back. These could be stored by the {@link Commander} class in a separate
 * database for reference (though we are not doing that here).
 */

public abstract class Service {
  
  protected final Database database;
  public ArrayList<Exception> exceptionsList;
  private static final String ALL_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
  private static final Hashtable<String, Boolean> USED_IDS = new Hashtable<String, Boolean>();

  protected Service(Database db, Exception...exc) {
    this.database = db;
    this.exceptionsList = new ArrayList<Exception>(Arrays.asList(exc));
  }

  public abstract String receiveRequest(Object...parameters) throws DatabaseUnavailableException;
  protected abstract String updateDb(Object...parameters) throws DatabaseUnavailableException;

  protected String generateId() {
    StringBuilder random = new StringBuilder();
    Random rand = new Random();
    while (random.length() < 12) { // length of the random string.
      int index = (int) (rand.nextFloat() * ALL_CHARS.length());
      random.append(ALL_CHARS.charAt(index));
    }
    String id = random.toString();
    if (USED_IDS.get(id) != null) {
      while (USED_IDS.get(id)) {
        id = generateId();
      }
    }
    return id;
  }
}
